Key takeaways
- Check for cracks first: a cracked part changes the whole decision
- Local wear on a sound part is the best case for repair
- Ask what wore the part, or it will wear again
- Old and obsolete machines are where repair or a new copy made from the old part pays off most
- Photos and measurements let a shop give you an opinion before the part moves
Every maintenance manager gets to this question with a broken part on the bench. A new part has a price and a wait. A repair has a price, a wait and a risk. The way to decide is to ask five plain questions, in order, before anything is ordered or cut.
1. Is the part cracked?
A crack decides most cases. On a magnetic metal such as steel or cast iron, Magnaflux inspection finds surface and near-surface cracks that the eye misses. A small crack at a weld toe can be ground out and rewelded. A crack that runs through a keyway root, a shaft shoulder or a thin web usually means the part has reached the end of its fatigue life, and a repair there only delays the failure.
2. How much metal is gone, and where?
Wear that is limited to a bearing seat, a seal diameter, a bore or a face can be built up and machined back to size. Wear spread through the whole part, or metal that has been eaten away by corrosion, has little left to rebuild.
If the worn area is a bearing or seal surface, the rebuild method matters. The guide on metal spray, sleeve or weld compares the three. Many of our shaft, pump and gearbox repairs are of this kind, and the metal spray page shows how the surface is rebuilt.
3. What wore it out?
A part that wore because it was never greased, because a seal let in dirt or because a bearing failed upstream will wear again if only the part is fixed. Look for the cause. A misaligned bore that cooked a bearing needs align boring so the new bearing sits on a true line. A repair that fixes the cause and the damage lasts.
4. Is a new part available?
For a current machine, a new part may be a catalog order away. For an older machine, or a one-off piece of plant equipment, the new part may no longer be made, may be a special order, or may be a casting that must be poured. This is where a repair, or a new part machined from the old one, tends to win. Our post on making a part that is no longer made goes through that path.
5. What does the down time look like?
Count the days the machine is stopped under each option: the wait for the new part to arrive, or the time for the repair, plus moving the part both ways. Include fitting. A repair that keeps a machine working is sometimes the right call even where a new part would be better, and a new part is sometimes the faster path even where repair is possible. Ask the shop for an opinion on the repair side while you ask the supplier for the new part.
A quick table
These are general rules of thumb, not promises for any one part.
| Situation | Lean toward |
|---|---|
| Sound part, worn bearing seat or seal area | Repair |
| Oval bore in a large housing | Repair |
| Crack through a shoulder or keyway root | Replace or make new |
| Part is bent through its length | Replace or make new |
| Obsolete part, no source for a new one | Repair or copy from the old part |
| Same part failing again and again | Fix the cause, then decide |
How to get an opinion from the shop
Send photos from several sides, close-ups of the worn area with a tape in the shot, the machine and part name, and any sizes you have. Attach them to the quote request, or call (775) 359-5570 Monday to Friday between 7:00 am and 3:30 pm. We work from your specifications, drawings or samples, so a worn part is enough to start, and consultations are free.
Sources
- Magnetic particle inspection (Wikipedia) (2026-10-18)
- Thermal spraying (Wikipedia) (2026-10-18)
- AGMA, American Gear Manufacturers Association (2026-10-18)
